This project is part of the Infant-Save Program of the Infant Primate Research Laboratory. We are developing the technology and methodology required to produce useable heart-rate data from freely interacting infant macaques as young as 3 4 months of age. Our ultimate goal is to measure heart-rate variability and to relate individual patterns in variability to levels of stereotypic behaviors in the infants. Included in these analyses will be behavioral measurements of social interaction and temperament, as well as stress measurements such as salivary cortisol.